Multi-tubular reactors with monolithic catalysts

Abstract

Multi-tubular reactors for fluid processing incorporate reactor tubes containing thermally conductive monolithic catalyst structures with relative dimensions and thermal expansion characteristics effective to establish both a non-interfering or slidably interfering fit between the monolith structures and the reactor tubes at selected monolith mounting temperatures, and geometries at reactor operating temperatures such that the operating gaps between tubes and monoliths under the conditions of reactor operation do not exceed about 250 μm over tube sections where high heat flux to or from the monoliths is required.

1. A method for assembling a multi-tubular reactor for processing a fluid stream in a processing temperature range, the reactor incorporating an array of reactor tubes filled with one or more monolith segments of a monolithic catalyst or catalyst support, which comprises the steps of:
 selecting a monolith segment of a monolithic catalyst or catalyst support structure, the segment being formed of a heat-conductive material having a first average linear coefficient of thermal expansion; 
 selecting a reactor tube formed of a heat-conductive material having a second average linear coefficient of thermal expansion, wherein the first average linear coefficient of thermal expansion is greater than the second average linear coefficient of thermal expansion; 
 sizing the monolith segment and/or the reactor tube to dimensions effective to provide (i) a non-interfering fit between the monolith segment and the reactor tube when each is at a selected monolith mounting temperature and when each is at ambient temperature at reactor shut-down, and (ii) an average gap distance between the reactor tube and the segment not exceeding about 250 μm when the monolith segment is filled with fluid at a temperature in the processing temperature range; and 
 inserting the segment into the reactor tube. 
 
     
     
       2. A method in accordance with  claim 1  wherein the step of sizing the monolith segment and/or the reactor tube involves the step of heating and/or cooling one or both of the monolith segment and reactor tube to a selected mounting temperature effective to provide a non-interfering fit therebetween. 
     
     
       3. A method in accordance with  claim 1  wherein the monolithic catalyst or catalyst support is a composite comprising a honeycomb core element and a metal jacketing element. 
     
     
       4. A method for processing a fluid stream in a processing temperature range, with a reactor incorporating an array of reactor tubes filled with one or more monolith segments of a monolithic catalyst or catalyst support, which comprises the steps of:
 selecting a monolith segment of a monolithic catalyst or catalyst support structure, the segment being formed of a heat-conductive material having a first average linear coefficient of thermal expansion; 
 selecting a reactor tube formed of a heat-conductive material having a second average linear coefficient of thermal expansion wherein the first average linear coefficient of thermal expansion is greater than the second average linear coefficient of thermal expansion; 
 inserting the monolith segment into the reactor tube to provide (i) a non-interfering fit between the monolith segment and the reactor tube when each is at a selected monolith mounting temperature and when each is at ambient temperature at reactor shut-down, and (ii) filling the monolith segment with fluid at a temperature in a processing temperature range to achieve an average gap distance between the reactor tube and the segment not exceeding about 250 μm. 
 
     
     
       5. A method in accordance with  claim 4 , which further comprises returning the reactor to the selected monolith mounting temperature with a non-interfering fit between the monolith segment and reactor tube.